Scheuch GmbH has developed a cascade classifier especially for filler removal in the gravel and crushed stone industry. The material is generally fed into the classifier on a belt conveyor and through a specially designed pendulum flap from the top. The pendulum flap minimizes the amount of air leaked into the classifier, therefore avoiding any adverse effects on the separation efficiency. The material flows from the top to the bottom over several cascades and the air necessary for classifying is sucked in from the bottom and blown in crosscurrent fashion through the material at high speed using the cascades, which function here as nozzles. This generates powerful shearing forces that separate the fine-grained from the coarse grained particles. The oversize content in the filler can be minimized and the filler removed more efficiently due to the more homogeneous air flow.